JVM probably has a better ecosystem, so Kotlin wins in that regard. I would also say there's a huge and painful difference between C# and TypeScript, which is t

JVM probably has a better ecosystem, so Kotlin wins in that regard. I would also say there's a huge and painful difference between C# and TypeScript, which is that C# has nominal typing (no equivalency between types unless they're literally the same) and TS has structural/duck typing (if the members of two objects are the same, they're equivalent). That makes sense because C# can be much lower level and has its own set of priorities during compilation, so I'm not really complaining. But ergonomically, you really miss the TS type system when you don't have it.